1. Field of the Invention
The present invention relates to an improved transport catheter, and more particularly to an improved catheter which can accept various probes for sensing biological conditions and parameters and which allows high fluid flow rate for introducing fluids irrespective of the presence of sensing instruments in the catheter, thereby reducing the risk of patient complications.
2. Description of the Prior Art
Numerous catheters exist for sensing, diagnosing and treating various biologic conditions. For example, there are cardiac catheters used for angioplasty, for measuring cardiac output, such as thermodilution catheters, pulmonary artery wedge pressure monitors, blood flow monitors and temperature monitors. In use, a transport catheter is initially introduced into an appropriate vessel or body cavity. In the case of a thermodilution catheter, for example, the transport catheter may be introduced into an appropriate vein. Thereafter, the thermodilution catheter is inserted and passed through the right atrium and ventricle and out to the pulmonary artery. After the catheter is properly positioned and the balloon inflated, various readings can be taken of left heart pressure, for example, and pulmonary artery temperature. The same measurements may be taken a number of times while the catheter is in place. However, if the patient's condition changes and requires other measurements or diagnosis, or additional information is desired, such as may be required in view of the results obtained by the thermodilution measurements, the thermodilution catheter must be removed and substituted with a different catheter for such measurements. The subsequent catheter exchange increases the possibility of infection through the introduction of a second catheter and increases the probability of other problems such as venous puncture.
Thermodilution catheters, such as the well known Swan-Ganz catheters, generally provide for introducing fluids into the patient through the catheter. However, some procedures require higher fluid flow rates or introduction of more viscous fluids than are presently contemplated with such catheters. Such catheters are generally not designed for maximum fluid flow or for efficient flow of relatively viscous fluids.
In the past, multi-lumen catheters were designed wherein the catheter body was divided into circular sections of similar size or substantially triangular sections to form the separate lumens. These catheters were generally too small to accept sensing probes and one or more of the lumens of such catheters occasionally become constricted at the seal of the transport catheter. A further disadvantage of these multi-lumen catheters becomes apparent if an ultrasound probe was to be used within one of the lumens of the catheter in order to obtain diagnostic readings. In this case, the similar sized lumens surrounding the probe-carrying lumen contain relatively large amounts of air space that cause undesirable attenuation of the ultrasonic signal.
There is therefore a need for an improved catheter which can accept a variety of successive probes or sensors or other instruments and which also, simultaneously, allows for high fluid flow for fluids to be introduced into the body, as well as the introduction of relatively viscous fluids. Additionally, a need also exists for a multi-lumen catheter that minimizes the sizes of the lumens which might contain ultrasonic wave attenuating air in lumens adjacent an instrument containing lumen.